Former Brazil star Ronaldo was admitted to hospital in Ibiza last Friday with a case of pneumonia.
The 41-year-old is said to have been diagnosed with the illness after being rushed to Can Misses Hospital on the island on Friday evening.
Respected island daily Diario de Ibiza said he had asked for a transfer to a private hospital called Clinica Nuestra Senora del Rosario just before midnight the same day.
It quoted hospital sources as saying he was still in intensive care but he was making good progress.
Staff at Can Misses Hospital said they were unable to give out any information for ‘data protection reasons.’
No-one at the private hospital Ronaldo is currently said to be a patient at could be contacted early on Sunday for comment.
Ronaldo, regarded as one of the world’s best-ever players, owns a house in Ibiza and is a regular visitor to the island.
He is believed to have arrived in Ibiza for a summer break a few days ago.
Ronaldo went down with dengue fever in January 2012 and posted a picture of himself on Twitter hooked up to a drip in hospital alongside the message: ‘Good morning to all those who began the New Year with dengue.’
He retired from football in 2011 after a glittering career with Barcelona, Inter Milan and Real Madrid.
Ronaldo finished his career with an impressive 414 goals, 62 of which came in just 98 appearances for the Brazilian national side.
He hit eight goals and scored in every match in Brazil’s 2002 World Cup win apart from the quarter-finals en route to lifting the trophy in Japan.
He finished his career with 12 goals in the World Cup finals, tying with Pele for the all-time record.
In his later years he battled with overweight because of a thyroid problem.